Transducers utilizing electrocapillary action

ABSTRACT

Transducers utilizing electrocapillary action for sensing force, pressure, acceleration motion, and/or vibration and producing an output voltage.

United States Patent 1 [111 3,889,086 Lucian 1 June 10, 1975 TRANSDUCERSUTILIZING [58] Field of Search 200/182, [91, I92, 193,

ELECTROCAPILLARY ACTION [76] Inventor: Arsene N. Lucian, PO. Box 300,

Manasquanj NJ 03736 [56] References Cited [22] Filed July 1 1974 UNITEDSTATES PATENTS 3,825,709 7/[974 Lucian 8. 200/192 [2!] Appl. No.:484,620

Related US. Application D t Primary ExaminerHerman J. Hohauser [63]Continuation-impart of Ser. No. 301,268, 0m. 2, F Darby 1972, Pat. No.3,825,709, which is a continuation-impart of Ser. No. 37,965, May 18,[57] ABSTRACT 1970, Pat. No. 3,70l,868.

Transducers utilizing electrocaplllary aCHOTl for sens- [52] U S Cl200/19} 2OO/2l4 335/49 ing force, pressure, acceleration motion, and/orvibra- 310/2; 179/! 33 non and producing an output voltage. [51 Int. Cl.HOlh 29/06 19 Claims, 6 Drawing Figures I4 H I I Q 26 l2 27 25 2| Q|4"'\ E L o .............,;a;'-.""" nwnaunn. g: Q ,1

PATENTEDJUH 10 ms SHEET FIG DIGITAL COMPUTER illIl-lllll iM-Ili E )1 N 46E 5 U6 P .L 2 N 5 O C R M A TRANSDUCERS UTILIZING ELECTROCAPILLARYACTION CROSS-REFERENC ES This application is a continuation-in-part ofmy prior copending application Ser. No. 301,268 filed Oct. 2, 1972, nowU.S. Pat. No. 3,825,709 issued July 23, 1974 which in turn is acontinuation-in-part of my prior copending application Ser. No. 37,965,filed May 18, I970, now U.S. Pat. No. 3,701,868 issued Oct. 31, I972.

The principles of the electrocapillary effect are discussed in myaforesaid U.S. Pat. No. 3,701,868. The application of the principles toswitching devices of various types and forms is disclosed in saidpatent. In the various devices of that patent the production ofmechanical motion and the consequent switching action were obtained bythe application of a small electromotive force (emf) across a singlemercury-electrolyte interface in a single bore tube (or multiplesthereof). This is the motor-action" phase of the electrocapillaryeffect.

In the aforesaid copending application the electrocapillary action isutilized in conjunction with external means to cause themercury-electrolyte interface to move in one direction or another and tothereby obtain a resultant emf, or voltage. This is the generatoraction" phase of the electrocapillary effect. In the copendingapplication several transducer devices utilizing this phase of theeffect are disclosed and claimed.

The aforesaid copending application also discloses that if the generatoreffect is revised and a motion of the mercury column is brought about bya casual effect (e.g. force, pressure, acceleration, impulse, etc.) 21voltage will be generated between the electrodes of the electrocapillarydevice.

The present invention is directed to several transducers operating onthe electrocapillary principle in which a motion of themercury-electrolyte interface is brought about by a variety of casualeffects, such as force, pressure, impulse, acceleration, temperature,electric or magnetic effects, optical effects, radiation, or othermeans. The transducers of this invention utilize the causal effect withactuating elements of the transducer or by a remote causal effectproducing an impingement of energy of any type upon the actuatingelements of the transducer. In either case an emf or voltage isgenerated between the electrodes of the electrocapillary transducerwhich is then available for further use or processing.

Transducers according to the present invention also may, in whole or inpart, be subject to relative motion with respect to their original spacecoordinates. Such relative motion in whole or in part, which may besmall or large in magnitude, may be used in diverse ways so that thetransducer performs sensor functions on the surface of the earth or inspace. These functions may include such things as: detection of seismicshocks and tremors caused by earthquakes or artificial man-madeexplosions of the type produced in prospecting for oil, gas, mineralsand so forth; intruder detection; sensing of passing vehicles andwalking personnel; and the sensing of acceleration in either terrestrialor extraterrestrial navigation and missle guidance systems as well as inother applicable situations.

It is therefore an object of this invention to provide various types oftransducers based on the electrocapillary effect, adapted for use assensor elements.

Another object is to provide various types of transducers based on theelectrocapillary effect adapted for detection of seismic disturbances ofgeophysical origin and of man-made or artificial explosions used inprospecting for oil, gas, minerals, etc.

A further object is to provide electrocapillary transducers for use as asensor means for detection of intruders in protected areas.

Another object is to provide electrocapillary transducers for sensingobjects or persons in motion such as used in the implementation ofautomatic equipment.

An additional object is to provide electrocapillary transducers for useas a sensor to detect the passage of vehicles in a given area as for thedetection of marching persons in or near the area.

A further object is to provide electrocapillary transducers for use assensors for the detection and measurement of all types of acceleration,on ground or in space.

A further object is to provide transducers based on the electrocapillaryeffect in which there is a single interface between a capillary columnof liquid conductive metal and an electrolyte solution in contacttherewith.

An additional object is to provide transducers based on theelectrocapillary effect in which a plurality of capillary columns ofliquid conductive metal are used in parallel, each column having asingle interface with an electrolyte solution.

Another object is to provide transducers based on the electrocapillaryeffect in which a plurality of sensor units are connected in series inorder to obtain an increased response voltage.

Yet another object is to provide an accelerometer based on theelectrocapillary effect in which there is a single interface between acapillary column of liquid conductive metal and an electrolyte solutionin contact therewith.

Other objects and advantages of the present invention will become moreapparent upon reference to the following specification and annexeddrawings in which:

FIG. 1 is a plan view in cross-section similar to FIG. 4 of thecopending application, showing portions of a transducer which may beused as a type of seismic sensor;

FIG. 1A is a view of a modification of the transducer of FIG. 1;

FIG. 2 is a plan view in cross-section of another form of sensor using adifferent type of suspension system for the sensors;

FIG. 3 is a plan view, partly in cross-section of an electrocapillaryaccelerometer made in accordance with the invention and its associatedelectronic circuitry',

FIG. 4 is a plan view partly in cross-section, of an electrocapillaryaccelerometer useful for detection and measurement of accelerations in avertical plane; and

FIG. 5 is a view of another embodiment of accelerometers.

The theory of the electrocapillary phenomenon is disclosed in theaforesaid patent and copending application, which disclosure isincorporated by reference, and will not be repeated here. In general,motion of an interface formed at the junction of a liquid metalcapillary column, such as mercury, and a capillary column of anelectrolyte in contact therewith, causes a voltage to be generatedbetween a pair of electrodes one of which is associated with the metaland the other of which is associated with the electrolyte.

FIG. 1 shows a transducer constructed according to the invention whichutilizes the electrocapillary effect. The transducer utilizes some ofthe components of the transducers of FIG. 4 of the aforesaid priorcopending application. Here a capillary tube 70 is located betweenreservoirs 72 and 74 at the ends thereof. Reservoir 72 has an opentubular arm 73 which is closed off by a highly resilient and flexiblebellows 79 which can be made, for example, of rubber, plastic or othersuitable material.

A pool of a metallic liquid 86, such as mercury, is located in reservoir72. The mercury extends part way up into the arm 73 leaving a pocket 77between the closed end of bellows 79 and the mercury in arm 73. Thepocket 77 can be filled with air, another suitable gas, or a liquidwhich will not mix with the mercury 86. A column of mercury 88 extendsinto the capillary tube 70.

The reservoir 74 includes a lower extension portion 78 which is tippedoff. The end of reservoir 74 is sealed off by an elastic membrane 80which can be of rubber, metal or other suitable material. A cap 82covers the membrane 80 leaving a pocket 83 therebetween. The pocket 83is filled with air or other highly compressible g The main portion ofreservoir 74 is filled with an electrolyte solution 87 and the reservoirextension 78 has a mercury pool 89. A first output terminal, orelectrode 90, passes through the tube into the reservoir 72 to have aportion of it in electrical contact with the mercury 86 and a secondoutput terminal 92 passes into the reservoir extension 78 to have aportion in electrical contact with the mercury pool 89.

A first, porous filter partition 96, for example of fritted glass, islocated between the end of capillary tube 70 and the reservoir 74 and asecond filter partition 98, which also can be of fritted glass, islocated between the mercury pool 89 and the electrolyte 87. Other filterpartitions of various degrees of porosity may be used in differentsections or locations of the transducer device, in order to make thetransducer operation more foolproof. A single interface 99 is formedbetween the column of mercury 88 and the electrolyte 87 in the capillarytube 70. The operation of the device is described below.

Applying a force to bellows 79 above the end of the column of mercury inarm 73 will cause an impulse of energy in the pocket of liquid or gas 77in the arm. This impulse is transmitted through the columns of mercuryin arm 73, and the mercury in reservoir 86 and in the column 88 todisturb the interface 99 between the mercury column and the electrolyteand to cause it to move. This motion causes a change in surface tensionat the single interface 99 and produces a voltage which appears acrossthe two terminals 90 and 92. The magnitude of the voltage depends uponseveral factors 1ncluding, for example, the amount of force appliedtothe mercury column 88, the size of the column, the size of theinterface, the suddenness or speed of application of the force, etc.

As the mercury column 88 moves, the electrolyte 87 in reservoir 74 willalso move causing the elastic mem brane 80 to move (expand as the columnmoves to the right). thereby compressing the gas in the pocket 83between the membrane and the cap 82. This absorbs the shock of theoriginal energy impulse. Once the force is released from the bellows 79,the gas in pocket 83 will expand and return the membrane 80 to itsinitial position. This will restore the system to an equilibriumcondition with the meniscus at the interface 99 approximately to thesame location. At this time, the voltage 0 which has been generatedacross the terminals 90 and 92 will drop back to zero. In some cases,depending upon the elasticity and reaction of the membrane 80, therewill be an overshoot of opposite polarity of the voltage produced acrossthe terminals 90 and 92. That is, there will be a movement of themercury column 88 to the left beyond its original position before theforce was applied to the bellows 79.

It should be understood that the response time of the production of thevoltage can be controlled by properly selecting the fluid or liquid inthe pocket 77 between the bellows 79 and the end of the mercury column86 in arm 73. That is, if an incompressible liquid is used in pocket 77,there will be a rapid, if not instantaneous 2S reaction of theproduction of the voltage when a force is applied to bellows 79. On theother hand, if a compressible medium is utilized in pocket 77, thereaction will be delayed by the amount of time it takes the forceapplied to the bellows 79 to compress the medium and move the body ofmercury 86. As should be apparent,

this provides a readily simple way of forming a controlled reactiontransducer with desired delay or response characteristics. It shouldalso be understood that the membrane 80 can be damped to control its re-5 sponse characteristics.

FIG. 1 shows a sensor assembly constructed in accordance with thepresent invention which utilizes a specific mode of application of theinertial force of a mass [0, which can be a ball or other suitableweight. The

mass 10 is suspended by a spring 12 from a horizontal support ofa frame14. The frame can be placed on the ground or on any support or locationcapable of transmitting a vibration or tremor. The electrocapillary tubecan be supported by frame 14 but is isolated therefrom.

The mass it) rests on a bar, or lever, 16, which can be bifurcated witha central space between its arms into which cthe mass can extend. Bar 16is pivotally mounted at one end 18 to the vertical support of the frameand point 18 serves as a fulcrum for the bar. The

lever and fulcrum are selected to obtain a desired mechanical advantage.A connecting rod 20 is attached to the bar 16 and has an end 21, in theshape of a disc, which engages the top of bellows 79. The mode ofoperation of sensor of FIG. 1 is described below. When frame 14 issubjected to a tremor or vibration, the suspended inertial mass 10 isset in vibratory motion, principally in a vertical up and downoscillation. The impulse generated by this vibration is transmitted bythe lever 16 to connecting rod 20 and through the rod 20 to the bellows79. The oscillatory motion of bellows 79 transmits a force through theintervening fluid or other medium 77 to the meniscus of the mercurycolumn.

This causes the entire Hg column, including the interface 99, tooscillate and thereby generate a voltage between circuit terminals 90and 92. Thus the sensing action is completed and translated into analternating current voltage. This voltage then can be fed intoappropriate electrical or electronic circuitry for processing and/orrecording.

The sensor of FIG. 1 also has a dual control knob 24a, 24b withconcentric shafts on the horizontal support of frame 14 which controls apair of fingers 25 and 26. The lower finger 25 engages the underside ofa fixed piece 27 on the mass 10. The mass can be moved and locked in agiven vertical position by adjusting knob 24a. With this operation theconnecting rod can be lifted or depressed slightly to vary its contactpressure with the top face of the bellows. to control the sensitivity ofthe transducer.

In a similar manner another control knob 24b operates a finger 26 tochange the active length of the spring, if such a change is desired tocontrol transducer sensitivity. The length of the lever arm of the forceexerted on the bellows 79, and hence the sensitivity of the transducer,may be changed by moving mass 10 along the upper support bar. That is,the upper end of spring 12 is mounted to a movable support.

As is known, the detection of vibrations and tremors occurring in theearth or on the surface of the earth depends primarily on the inertialresponse of a mass suspended so as to be capable of responding todisturbances of various types, frequencies and intensities in anydirection and in any plane. The sensor of FIG. 1 is capable of suchresponse and is capable of use in many instances where, heretofore,instruments such as seis mographs, seisometers, geophones and similardevices, were used. The sensor of H0. 1 has applicability in measuringshocks caused by earthquakes and manmade shocks produced in theexploration for oil, gas, minerals, and other natural resources. Inaddition, it can respond to vibrations, such as caused by movement of aperson or animal in a protected area, to serve as an intruder detectiondevice. Further, it can respond to moving personnel and/or movingvehicles.

FIG. 1A shows a modification of the mass suspension system for atransducer of the type shown in FIG. 1. Here, the inertial mass 10 islocated within a cylindrical guide sleeve 100 whose internal diameter isslightly greater than that of the mass. The sleeve is preferably of amaterial whose inner surface has a minimal frictional resistance. Asuitable material is TEFLON. A slot 110 is provided in the sleeve foradjustment purposes and the mass is suspended from a spring 11b whoseupper end is attached to a fixed member. The operation of this system isas described with respect to FIG. I. The mass 10, in either case. can beof any other suitable shape.

FIG. 2 shows a modification of the transducer of FIG. 1. Here the mass10 rests directly on top of bellows 79 and is supported by a wire, orpin, or spring, 30 which is attached to a yoke 32a which is slidablealong a lever 32 which is, in the preferred embodiment, a leaf spring.The yoke 32a is attached to the frame 14 by flexible wire or a coilspring 38. Spring 38 in cooperation with leaf spring 32 controls andstabilizes the rest position of the mass 10 supported by the leafspring. The response frequencies of leaf spring 32 and coil spring 38can be so adjusted that the elastic response of each member (to incidentvibration or tremor) will cooperate with and reinforce the response ofthe other, thus resulting in much greater sensitivity. The free periodof resonant frequency of both members would have to be far removed fromthe level of frequencies they are expected to sense or detect. The yoke32a can be moved along the leaf spring 32 to change the length of thelever arm and the transducer sensitivity. The end of the leaf spring 32remote from the mass is connected at a fulcrum point 34 to a bracket 36which is mounted to the support arm 14. The bracket 36 also can be movedalong the frame 14 to keep the mass 10 centered on bellows 79.

The transducer of FIG. 2 operates in the same manner as that of FIG. 1and the construction of the electrocapillary device below and to theright of the arm 73 is the same or similar to that shown in FIG. 1.Therefore, a description of the electrocapillary device will not berepeated. Both types of transducers have at least one importantadvantage over seismometers which utilize sensing by means ofa change inan electromagnetic field. In using an electro-magnetic type seismometer,the location for the instrument must be selected carefully. There isalways the possibility of serious electrical interference if theinstrument is placed in a location where strong electromagnetic fieldsexist, such as hightension transmission lines, electrical powergenerating stations, and other interference-producing machinery andequipment. It is needless to repeat that the electrocapillary sensor isnot subject to any such interference. Another advantage of theelectrocapillary sensor resides in the fact that it possesses muchgreater flexibility in adjusting or changing the sensitivity of thesystem internally as compared to a mechanical or electromagnetic sensorsystem.

FIG. 3 shows a transducer constructed in accordance with the inventionwhich is used as an accelerometer for sensing acceleration force alongeither the horizontal or vertical axis. The same reference numerals havebeen used for similar components. Here, the mercury reservoir 72 end ofthe tube is closed off at 40. A frictionless slidable piston 42, whichcan be cup or disc shaped, is located in this end of the tube. A spring42a is connected between the piston 42 and the end of the tube. Thespring may be of the compression type and is constructed to obeyaccurately a given physical law, for example, Hookes law. A similarpiston and spring arrangement 43, 43a, of equal strength, is located atthe other end of the tube in the electrolyte section. The interface ormeniscus 99 is held in a null or equilibrium position under the opposingconstraints of the two equal spring systems.

To explain the operation of the accelerometer of FIG. 3, consider thatthere is the platform on which the accelerometer is mounted which issubjected to an acceleration with a component along the longitudinalaxis of the instrument and directed from left to right in the diagram.The inertial reaction force of the mass of met cury 86 will act upon thepiston and spring 42, 42a, and move the piston 42 a certain distance Ato the left of its rest position. This action will also move interface99 a corresponding distance A to the left. This distance A isproportional to the acceleration. If the acceleration remains constant,the distance A will remain fixed. If the acceleration is variable, thenthe distance A will also vary in accordance with variations of theacceleration. The movement of piston 42 causes the mercury column 88 andthe electrolyte 87 to move thereby moving the piston 43. In the exampledescribed, the piston 43 moves downwardly extending the spring 430. Whenthe acceleration is removed, spring 42a will extend and spring 430 willcompress to restore the system to its equilibrium condition. When thecomponent of acceleration is in the opposite direction from thatdescribed, the pistons will move oppositely.

The measurement of acceleration is a rather complicated problem. Itinvolves a clear understanding of inertial reaction force in contrastwith other kinds of forces, such as gravitational force, centrifugalforce, viscosity force, electro-magnetic force, etc. In general it canbe said that in a practical instrument, one would have to take intoaccount the interaction between the fundamental force of inertialreaction with one or more of the other forces that come into play in thedesign of an accelerometer.

One of the features of the electrocapillary accelerometer is that anymovement of the interface 99 will automatically generate a voltage atterminals 90, 92. In this case, the voltage will be proportional to theacceleration. Therefore, a variable acceleration, which normally happensin practice, will generate a variable voltage.

The variable voltage produced by the accelerometer can be modified toyield a regular train of pulses or waves to be fed into a digitalcomputer. Typical circuitry to accomplish this objective is also shownin FIG. 3. Here, the voltage produced at terminal 90, terminal 92 beinggrounded, is applied to the input ofa high gain amplifier 50 whoseoutput controls the frequency of a voltage controlled oscillator 52. Theoutput of oscillator 52 is applied to pulse generator 54 of suitableconstruction which produces pulses at a rate corresponding to thefrequency of the signal from oscillator 52. The output pulses fromgenerator 54 can be applied directly to a digital computer 56 or anytype of data processing system. This is a standard analog to digitalconverter circuit whose components are conventional. The entire systemcan generally be classified as a single integrating accelerometer.

The accelerometer of FIG. 3 can be used in a vertical as well as ahorizontal position. For use in the vertical position it is preferred touse the construction for the electrolyte arm of the capillary system ofFIG. 1. The spring system 42,42a and 43,43a can be retained or can bereplaced by a suitable diaphragm equivalent or still another type offlexible bellows system as long as the restrained, elastic forces canaccurately respond to acceleration forces impinging on the inertial massof mercury and hold the meniscus 99 in any given equilibrium position.

FIG. 4 shows an embodiment of an electrocapillary transducer designedspecifically for use as a vertical accelerometer. Here, theelectrocapillary devices of FIGS. l-3 have been changed to include afirst tube 160 which contains the mercury column 162. The top end of themercury column is closed off by a member 164, slidable without friction,to which is attached spring 420, preferably constructed to follow HookesLaw, and the piston 42.

A second tube 170 is provided containing the electrolyte 172. The bottomend of the tube is bulb-shaped at 174 and contains a small quantity ofmercury I76 therein. The two tubes I60 and 170 are joined by a capillarytube 180 which is generally S-shaped. The single interface 182 occurs inthe capillary tube 180. The top of the electrolyte tube 170 is sealedoff by a member 186 to which is connected spring 43a and piston 43. Anelectrode 187 is immersed in the mercury pool 176 and an electrode 188in the mercury column 162.

The operation of the vertical accelerometer of FIG. 4 is similar to thatof the horizontal accelerometer of FIG. 3. Namely, any component ofvertical inertial ac celeration will cause the motion of the inertialmass, i.e. the mercury column, to initiate the motion responsive to theacceleration force acting on the whole system. The initial action of themercury column causes pistons 42,43 to move and the springs 42a, 43a toelongate or compress without any interference due to gravitationalacceleration. This moves the mercury column I62 and the interface 182 togenerate a voltage across the two terminals 187 and 188. The voltagegenerated can be gonverted into digital form using the circuitry of FIG.

In the vertical accelerometer of FIG. 4, the electrocapillary forceoffsets and counterbalances the gravltational force at the interface.Therefore, the mercury column responds only to the inertial forces. Thisgreatly simplifies the design and operation of an accelerometer.

In each of the embodiments of accelerometers of FIGS. 3 and 4, there areno mechanical or electromechanical pickoffs needed to produce thevoltage. Instead, the voltage corresponding to the inertial accelerationcomponent is generated directly at the terminals of the electrocapillarydevice.

FIG. 5 shows a further embodiment which can be used as a linearintertial accelerometer and in which two electrocapillary transducerscan be connected in series to increase the voltage sensed. Thisembodiment is a modification of the transducer shown in FIG. 3 and thesame reference numbers used where applicable. Here there are twoelectrocapillary arms 202a and 202b extending from adjoining butseparate mercury reservoirs 200a and 20019 which is a part of thecomplete envelope. The construction and action of the spring systemformed by elements 42 and 420 will not be repeated. An output voltagefor arm 202a is taken across terminals a and 92a and a bias voltage issupplied thereto by a source 2050 if needed for circuit adustment orsensitivity control purposes. Similarly, the output voltage of the arm202b is taken across the terminals 92a, 92b. Each of theelectrocapillary tubes has a single interface 99 between the mercury andthe electrolyte.

A main elastic diaphragm 215 is mounted in the reservoir 200. Thisdiaphragm is responsive to accelerations to change its position andthereby change the position of the meniscus in each of the arms 202 togenerate the voltage across the respective pairs of electrodes 90, 92.For example, assuming a component of acceleration is sensed which willmove the diaphragm M5 to the left, the length of the mercury column inarm 2020 is increased while the length of the mercury column in arm 202bis moved to its left and decreased. This will disturb the interface ineach column and produce a voltage across each of the sets of terminals900, 92a and 92b of opposite polarity. The two voltages can be addedalgebraically to double the total voltage. This voltage can be then usedin any desired manner to indicate the component of acceleration.

The piston and spring 42,420 at each end of the device will becompressed or extended depending upon the direction of movement of themercury columns. When the acceleration component is removed, the springsystem will restore the device to an equilibrium condition. Thediaphragm 215 can be replaced by other suitable responsive devices, forexample a spring system obeying Hookes Law.

What is claimed is:

I. An electrocapillary transducer comprising an envelope including atube portion having capillary transverse interior dimensions, a metallicliquid contained within said envelope and extending into said tubeportion, a liquid electrolyte contained within said envelope andextending into said tube portion, said metailic liquid and saidelectrolyte being immiscible in each other and forming a singleinterface only in said capillary tube, electrode means respectively inelectrical contact with said metallic liquid and said electrolyte, meansexternal of said envelope for applying a force across said metallicliquid and said electrolyte effective to move the interface of saidliquids and to change the interfacial tension between said liquids toproduce a voltage at said electrodes due to the electrocapillary effect,said means including means for sealing off an end of said envelope, asuspended mass responsive to vibrations to cause movement thereof forproducing corresponding movement of said sealing means, and a materialbetween said sealing means and one of said liquids for transmitting theforce to the said one liquid.

2. An electrocapillary transducer as in claim 1, wherein said sealingmeans comprises a bellows which is directly acted upon by the vibrationsof said mass.

3. An electrocapillary transducer as in claim 1, further comprising aspring for suspending the mass.

4. An electrocapillary transducer as in claim 2, further comprisingmeans for adjusting the length of the spring.

5. An electrocapillary transducer as in claim 1, further comprising alever arm pivotally mounted about a point, said mass engaging said leverarm at a point spaced from its pivot point to provide a mechanicaladvantage.

6. An electrocapillary transducer as in claim 5, further comprisingmeans for adjusting the spacing between the pivot point and the point ofengagement with the mass.

7. An electrocapillary transducer comprising an envelope including atube portion having capillary transverse interior dimensions, a metallicliquid contained within said envelope and extending into said tubeportion, a liquid electrolyte contained within said envelope andextending into said tube portion, said metallic liquid and saidelectrolyte being immiscible in each other and forming a singleinterface only in said capillary tube, electrode means respectively inelectrical contact with said metallic liquid and said electrolyte, meansresponsive to a component of physical acceleration for applying a forceacross said metallic liquid and said electrolyte in response to acomponent of physical acceleration to move the interface of said liquidsand to change the interfacial tension between said liquids to produce avoltage at said electrodes due to the electrocapillary effect.

8. An electrocapillary transducer as in claim 7, wherein said meansresponsive to the component of physical acceleration comprises aflexible membrane.

9. An electrocapillary transducer as in claim 7, wherein said meansresponsive to the component of physical acceleration comprises a springmember.

10. An electrocapillary transducer as in claim 7, further comprisingmeans for converting the voltage produced at said electrodes intodigital signals.

11. An electrocapillary transducer as in claim 7, wherein said envelopecomprises a first tube containing said metallic liquid and a second tubecontaining said electrolyte, said capillary tube connecting said firstand second tubes and said means responsive to the component of physicalacceleration acting on the liquid in one of said first and second tubes.

12. An electrocapillary transducer as in claim 7 wherein said envelopeincludes a reservoir portion con taining one of said metallic andelectrolyte liquids and a pair of tube portions of capillary transverseinterior dimensions in communication therewith, said metallic liquid andsaid electrolyte extending into each of said tube portions to establisha respective single interface therein, said electrode means being inelectrical contact with the metallic liquid and electrolyte in each ofsaid tube portions, and said means responsive to said component ofphysical acceleration adapted to move the interface on each said tubeportion.

13. An electrocapillary transducer as in claim 12 wherein saidacceleration responsive means includes a part located in said reservoirmeans to act on the liquids therein.

14. An electrocapillary transducer as in claim 13 wherein saidacceleration responsive means comprises a piston.

15. An electrocapillary transducer as in claim 7 wherein said capillarytube portion is generally vertical.

16. A transducer as in claim 15 wherein said interface lies in agenerally horizontal plane.

17. A transducer as in claim 7 wherein said envelope has at least oneportion extending generally vertically for holding said electrolyte andsaid liquid metal.

18. A transducer as in claim 17 wherein said capillary tube portion isgenerally vertical.

19. An electrocapillary transducer as in claim 7 wherein said meansresponsive to the component of physical acceleration comprises a movablepiston.

1. An electrocapillary transducer comprising an envelope including atube portion having capillary transverse interior dimensions, a metallicliquid contained within said envelope and extending into said tubeportion, a liquid electrolyte contained within said envelope andextending into said tube portion, said metallic liquid and saidelectrolyte being immiscible in each other and forming a singleinterface only in said capillary tube, electrode means respectively inelectrical contact with said metallic liquid and said electrolyte, meansexternal of said envelope for applying a force across said metallicliquid and said electrolyte effective to move the interface of saidliquids and to change the interfacial tension between said liquids toproduce a voltage at said electrodes due to the electrocapillary effect,said means including means for sealing off an end of said envelope, asuspended mass responsive to vibrations to cause movement thereof forproducing corresponding movement of said sealing means, and a materialbetween said sealing means and one of said liquids for transmitting theforce to the said one liquid.
 2. An electrocapillary transducer as inclaim 1, wherein said sealing means comprises a bellows which isdirectly acted upon by the vibrations of said mass.
 3. Anelectrocapillary transducer as in claim 1, further comprising a springfor suspending the mass.
 4. An electrocapillary transducer as in claim2, further comprising means for adjusting the length of the spring. 5.An electrocapillary transducer as in claim 1, further comprising a leverarm pivotally mounted about a point, said mass engaging said lever armat a point spaced from its pivot point to provide a mechanicaladvantage.
 6. An electrocapillary transducer as in claim 5, furthercomprising means for adjusting the spacing between the pivot point andthe point of engagement with the mass.
 7. An electrocapillary transducercomprising an envelope including a tube portion having capillarytransverse interior dimensions, a metallic liquid contained within saidenvelope and extending into said tube portion, a liquid electrolytecontained within said envelope and extending into said tube portion,said metallic liquid and said electrolyte being immiscible in each otherand forming a single interface only in said capillary tube, electrodemeans respectively in electrical contact with said metallic liquid andsaid electrolyte, means responsive to a component of physicalacceleration for applying a force across said metallic liquid and saidelectrolyte in response to a component of physical acceleration to movethe interface of said liquids and to change the interfacial tensionbetween said liquids to produce a voltage at said electrodes due to theelectrocapillary effect.
 8. An electrocapillary transducer as in claim7, wherein said means responsive to the component of physicalacceleration comprises a flexible membrane.
 9. An electrocapillarytransducer as in claim 7, wherein said means responsive to the componentof physical acceleration comprises a spring member.
 10. Anelectrocapillary transducer as in claim 7, further comprising means forconverting the voltage produced at said electrodes into digital signals.11. An electrocapillary transducer as in claim 7, wherein said envelopecomprises a first tube containing said metallic liquid and a second tubecontaining said electrolyte, said capillary tube connecting said firstand second tubes and said means responsive to the component of physicalacceleration acting on the liquid in one of said first and second tubes.12. An electrocapillary tRansducer as in claim 7 wherein said envelopeincludes a reservoir portion containing one of said metallic andelectrolyte liquids and a pair of tube portions of capillary transverseinterior dimensions in communication therewith, said metallic liquid andsaid electrolyte extending into each of said tube portions to establisha respective single interface therein, said electrode means being inelectrical contact with the metallic liquid and electrolyte in each ofsaid tube portions, and said means responsive to said component ofphysical acceleration adapted to move the interface on each said tubeportion.
 13. An electrocapillary transducer as in claim 12 wherein saidacceleration responsive means includes a part located in said reservoirmeans to act on the liquids therein.
 14. An electrocapillary transduceras in claim 13 wherein said acceleration responsive means comprises apiston.
 15. An electrocapillary transducer as in claim 7 wherein saidcapillary tube portion is generally vertical.
 16. A transducer as inclaim 15 wherein said interface lies in a generally horizontal plane.17. A transducer as in claim 7 wherein said envelope has at least oneportion extending generally vertically for holding said electrolyte andsaid liquid metal.
 18. A transducer as in claim 17 wherein saidcapillary tube portion is generally vertical.
 19. An electrocapillarytransducer as in claim 7 wherein said means responsive to the componentof physical acceleration comprises a movable piston.